From: "Thomas Weißschuh" <thomas.weissschuh@linutronix.de>
To: Andy Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Arnd Bergmann <arnd@arndb.de>,
"David S. Miller" <davem@davemloft.net>,
Andreas Larsson <andreas@gaisler.com>,
Nick Alcock <nick.alcock@oracle.com>,
John Stultz <jstultz@google.com>,
Stephen Boyd <sboyd@kernel.org>,
John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
Shuah Khan <shuah@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Theodore Ts'o <tytso@mit.edu>,
"Jason A. Donenfeld" <Jason@zx2c4.com>,
Russell King <linux@armlinux.org.uk>,
Madhavan Srinivasan <maddy@linux.ibm.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Nicholas Piggin <npiggin@gmail.com>,
Christophe Leroy <christophe.leroy@csgroup.eu>,
Huacai Chen <chenhuacai@kernel.org>,
WANG Xuerui <kernel@xen0n.name>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
Heiko Carstens <hca@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Sven Schnelle <svens@linux.ibm.com>,
Nagarathnam Muthusamy <nagarathnam.muthusamy@oracle.com>,
Shannon Nelson <sln@onemain.com>
Cc: linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org,
linux-kselftest@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linuxppc-dev@lists.ozlabs.org, loongarch@lists.linux.dev,
linux-mips@vger.kernel.org, linux-s390@vger.kernel.org,
"Thomas Weißschuh" <thomas.weissschuh@linutronix.de>
Subject: [PATCH v3 18/36] random: vDSO: split out datapage update into helper functions
Date: Wed, 17 Sep 2025 16:00:20 +0200 [thread overview]
Message-ID: <20250917-vdso-sparc64-generic-2-v3-18-3679b1bc8ee8@linutronix.de> (raw)
In-Reply-To: <20250917-vdso-sparc64-generic-2-v3-0-3679b1bc8ee8@linutronix.de>
Some upcoming changes will introduce additional callers of them.
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
---
drivers/char/random.c | 51 +++++++++++++++++++++++++++++++++------------------
1 file changed, 33 insertions(+), 18 deletions(-)
diff --git a/drivers/char/random.c b/drivers/char/random.c
index b0b88c6f6a1afcdb770e39b7a64cb3408e33bd2c..73c53a4fb949bfd2ed723fa3cec3fe0d066a7fa3 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -246,6 +246,37 @@ static unsigned int crng_reseed_interval(void)
/* Used by crng_reseed() and crng_make_state() to extract a new seed from the input pool. */
static void extract_entropy(void *buf, size_t len);
+/* This updates the generation in the vDSO data page */
+static void random_vdso_update_generation(unsigned long next_gen)
+{
+ if (!IS_ENABLED(CONFIG_VDSO_GETRANDOM))
+ return;
+
+ /* base_crng.generation's invalid value is ULONG_MAX, while
+ * vdso_k_rng_data->generation's invalid value is 0, so add one to the
+ * former to arrive at the latter. Use smp_store_release so that this
+ * is ordered with the write above to base_crng.generation. Pairs with
+ * the smp_rmb() before the syscall in the vDSO code.
+ *
+ * Cast to unsigned long for 32-bit architectures, since atomic 64-bit
+ * operations are not supported on those architectures. This is safe
+ * because base_crng.generation is a 32-bit value. On big-endian
+ * architectures it will be stored in the upper 32 bits, but that's okay
+ * because the vDSO side only checks whether the value changed, without
+ * actually using or interpreting the value.
+ */
+ smp_store_release((unsigned long *)&vdso_k_rng_data->generation, next_gen + 1);
+}
+
+/* This sets is_ready in the vDSO data page */
+static void random_vdso_set_ready(void)
+{
+ if (!IS_ENABLED(CONFIG_VDSO_GETRANDOM))
+ return;
+
+ WRITE_ONCE(vdso_k_rng_data->is_ready, true);
+}
+
/* This extracts a new crng key from the input pool. */
static void crng_reseed(struct work_struct *work)
{
@@ -272,22 +303,7 @@ static void crng_reseed(struct work_struct *work)
if (next_gen == ULONG_MAX)
++next_gen;
WRITE_ONCE(base_crng.generation, next_gen);
-
- /* base_crng.generation's invalid value is ULONG_MAX, while
- * vdso_k_rng_data->generation's invalid value is 0, so add one to the
- * former to arrive at the latter. Use smp_store_release so that this
- * is ordered with the write above to base_crng.generation. Pairs with
- * the smp_rmb() before the syscall in the vDSO code.
- *
- * Cast to unsigned long for 32-bit architectures, since atomic 64-bit
- * operations are not supported on those architectures. This is safe
- * because base_crng.generation is a 32-bit value. On big-endian
- * architectures it will be stored in the upper 32 bits, but that's okay
- * because the vDSO side only checks whether the value changed, without
- * actually using or interpreting the value.
- */
- if (IS_ENABLED(CONFIG_VDSO_GETRANDOM))
- smp_store_release((unsigned long *)&vdso_k_rng_data->generation, next_gen + 1);
+ random_vdso_update_generation(next_gen);
if (!static_branch_likely(&crng_is_ready))
crng_init = CRNG_READY;
@@ -741,8 +757,7 @@ static void __cold _credit_init_bits(size_t bits)
if (static_key_initialized && system_unbound_wq)
queue_work(system_unbound_wq, &set_ready);
atomic_notifier_call_chain(&random_ready_notifier, 0, NULL);
- if (IS_ENABLED(CONFIG_VDSO_GETRANDOM))
- WRITE_ONCE(vdso_k_rng_data->is_ready, true);
+ random_vdso_set_ready();
wake_up_interruptible(&crng_init_wait);
kill_fasync(&fasync, SIGIO, POLL_IN);
pr_notice("crng init done\n");
--
2.51.0
next prev parent reply other threads:[~2025-09-17 14:04 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-17 14:00 [PATCH v3 00/36] sparc64: vdso: Switch to the generic vDSO library Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 01/36] selftests: vDSO: vdso_test_correctness: Handle different tv_usec types Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 02/36] arm64: vDSO: getrandom: Explicitly include asm/alternative.h Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 03/36] arm64: vDSO: gettimeofday: Explicitly include vdso/clocksource.h Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 04/36] arm64: vDSO: compat_gettimeofday: Add explicit includes Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 05/36] ARM: vdso: gettimeofday: " Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 06/36] powerpc/vdso/gettimeofday: Explicitly include vdso/time32.h Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 07/36] powerpc/vdso: Explicitly include asm/cputable.h and asm/feature-fixups.h Thomas Weißschuh
2025-09-17 14:41 ` Christophe Leroy
2025-09-17 15:21 ` Thomas Weißschuh
2025-09-17 15:23 ` Christophe Leroy
2025-09-22 2:44 ` Michael Ellerman
2025-09-17 14:00 ` [PATCH v3 08/36] LoongArch: vDSO: Explicitly include asm/vdso/vdso.h Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 09/36] MIPS: vdso: Add include guard to asm/vdso/vdso.h Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 10/36] MIPS: vdso: Explicitly include asm/vdso/vdso.h Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 11/36] random: vDSO: Add explicit includes Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 12/36] vdso/gettimeofday: " Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 13/36] vdso/helpers: Explicitly include vdso/processor.h Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 14/36] vdso/datapage: Remove inclusion of gettimeofday.h Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 15/36] vdso/datapage: Trim down unnecessary includes Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 16/36] random: vDSO: trim vDSO includes Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 17/36] random: vDSO: remove ifdeffery Thomas Weißschuh
2025-09-17 14:00 ` Thomas Weißschuh [this message]
2025-09-17 14:00 ` [PATCH v3 19/36] random: vDSO: only access vDSO datapage after random_init() Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 20/36] s390/time: Set up vDSO datapage later Thomas Weißschuh
2025-09-17 15:12 ` Heiko Carstens
2025-09-17 14:00 ` [PATCH v3 21/36] vdso/datastore: Reduce scope of some variables in vvar_fault() Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 22/36] vdso/datastore: Drop inclusion of linux/mmap_lock.h Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 23/36] vdso/datastore: Map pages through struct page Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 24/36] vdso/datastore: Allocate data pages dynamically Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 25/36] sparc64: vdso: Link with -z noexecstack Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 26/36] sparc64: vdso: Remove obsolete "fake section table" reservation Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 27/36] sparc64: vdso: Replace code patching with runtime conditional Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 28/36] sparc64: vdso: Move hardware counter read into header Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 29/36] sparc64: vdso: Move syscall fallbacks " Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 30/36] sparc64: vdso: Introduce vdso/processor.h Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 31/36] sparc64: vdso: Switch to the generic vDSO library Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 32/36] sparc64: vdso2c: Drop sym_vvar_start handling Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 33/36] sparc64: vdso2c: Remove symbol handling Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 34/36] sparc64: vdso: Implement clock_gettime64() Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 35/36] clocksource: remove ARCH_CLOCKSOURCE_DATA Thomas Weißschuh
2025-09-17 14:00 ` [PATCH v3 36/36] clocksource: drop include of asm/clocksource.h from linux/clocksource.h Thomas Weißschuh
2025-09-20 13:24 ` [PATCH v3 00/36] sparc64: vdso: Switch to the generic vDSO library John Paul Adrian Glaubitz
2025-09-20 14:37 ` Thomas Weißschuh
2025-09-21 5:05 ` John Paul Adrian Glaubitz
2025-09-24 7:40 ` John Paul Adrian Glaubitz
2025-09-24 8:07 ` Thomas Weißschuh
2025-09-24 8:28 ` John Paul Adrian Glaubitz
2025-09-24 11:35 ` Thomas Weißschuh
2025-09-26 13:53 ` Andreas Larsson
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